Field of the Invention
The present invention relates to a display control device and a control method therefor.
Description of the Related Art
Displays for business, or the like, are calibrated in order to reduce changes in display quality with the passage of time. In the calibration (CAL), a white or gray image (referred to hereinbelow as “patch image”) is displayed on a display screen, and the brightness and chromaticity of the patch image are repeatedly measured using a colorimeter (CAL sensor).
In the calibration, the display quality (display characteristic) is adjusted such that the brightness and chromaticity are brought close to the desired values on the basis of colorimetry results obtained for a plurality of patch images.
FIG. 2 shows an example of display and colorimetry sequence for patch images in the calibration. In FIG. 2, the transverse direction represents the passage of time. In the example depicted in FIG. 2, patch images are repeatedly displayed in the order of (n−1)-th patch image, n-th patch image, and (n+1)-th patch image and colorimetry is performed. The colorimetry is performed within a period of time in which the patch images are displayed. Since the display quality is adjusted such that the brightness and chromaticity are brought close to the desired values on the basis of colorimetry results, a long time is required to execute the calibration. For example, about 10 min are needed for one calibration cycle.
Further, in order to improve the calibration accuracy, it is important to measure accurately the brightness and chromaticity of the display screen with a colorimeter. In order to increase the accuracy of colorimetry, it is important not only to improve the performance of the colorimeter itself in terms of the accuracy of colorimetry, but also to arrange the display and colorimeter at correct positions. Where the colorimeter is not arranged at a correct position with respect to the display screen, the accuracy of colorimetry is sometimes degraded and the target display quality cannot be reached.
Where buttons on the display body are operated or an image cable is inserted or removed during the calibration, the arrangement position of the colorimeter relative to the display screen can change significantly. In such a case, the colorimetry of the patch images cannot be normally performed because the accuracy of colorimetry is degraded by such significant change in the arrangement position. Where the calibration is continued in a state in which the colorimetry cannot be normally performed, the colorimetry results become abnormal and the calibration can eventually fail. Thus, since the calibration fails when it is continued in a state with the decreased accuracy of colorimetry, the user wastes time.
Japanese Patent Application Publication No. 2009-60221 relates to determining whether or not a color chart, which is outputted when data are created for printer calibration, is arranged correctly in a colorimeter. The determination is made for each color chart on the basis of a determination rule, which is created on the basis of output indication values of a specific patch in the color chart, and the actual colorimetry results for the color chart.
In display calibration, the calibration can fail when the colorimetry fails even for one patch image. The failure of calibration, as referred to herein, is for example, the case in which the display is not adjusted to the desired display characteristic. Therefore, the colorimetry needs to be accurately performed for all of the patch images. In order to perform the colorimetry accurately for a patch image, it is necessary that the accuracy of colorimetry performed by the colorimeter itself be good and that the colorimeter be correctly arranged with respect to the display. The calibration can fail even when the colorimeter arrangement position is slightly changed. Accordingly, determining whether or not the colorimeter (CAL sensor) is correctly arranged with respect to the display for each cycle of patch image colorimetry can be considered as a measure for preventing the calibration failure.
However, where the determination as to whether or not the colorimeter is correctly arranged with respect to the display is performed for each cycle of patch image colorimetry, the number of determination processing cycles increases and the calibration execution time is extended. For example, the calibration that has been conventionally completed in 10 min requires 15 min.
Meanwhile, where the calibration is performed without determining whether or not the colorimeter is correctly arranged with respect to the display, the calibration is completed in 10 min, but where the calibration fails, the 10 min are wasted.